Sondes with articulated arms used in well logging

ABSTRACT

Apparatus for use in making measurement in a well bore includes an elongated body member having at least one pair of wallengaging members articulated on the body member by arms for lateral movement between retracted positions alongside the body member and extended positions in contact with a well bore wall. Spring means are mounted externally of the body member and function to constantly urge the members outwardly, and means are provided for retracting the members, including a driven member movable upwardly on said body member, and means responsive to upward movement of said driven member for causing said wallengaging members to move toward retracted positions.

United States Patent Planche 1 SONDES WITH ARTICULATED ARMS USED IN WELLDOGGING [72] inventor: Jean Planche, LHay-Les-Roses, Val de Marne,France [73] Assignee: Schlumherger Technology Corporation, New York, NY.

[22] Filed: Feb. 16, 1971 [21] Appl. No.: 115,767

Related [3.8. Application Data [63] Continuation of Ser. No. 770,978,Oct. 28,

1968, abandoned.

[30] Foreign Application Priority Data Nov. 2, 1967 France ..67l26822[52] US. Cl. ..33/178 F, 33/2055 [51] Int. Cl.......G0lb 5/08, GOlb7/l2, GOlb 13/08, GOlb 5/08 [58] FieldofSearch ..33/l78 F [56]References Cited UNlTED STATES PATENTS 3,1 l7,938 4/l965 Roussin..33/l78 F [151 3,685,158 1 Aug. 22, 1972 Primary EXdmiMr-MOIIEH'CIForman Assistant Examiner-Paul G. Foldes Attorney-Emest R. Archambeau,.Ir., John P. Sennat, David l... Masley, Edward M. Roney, William R.Sherman and Stewart F. Moore [57] ABSTRACT Apparatus for use in makingmeasurement in a well bore includes an elongated body member having atleast one pair of wall-engaging members articulated on the body memberby arms for lateral movement between retracted positions alongside thebody member and extended positions in contact with a well bore wall.Spring means are mounted externally of the body member and function toconstantly urge the members outwardly, and means are provided forretracting the members, including a driven member movable upwardly onsaid body member, and means responsive to upward movement of said drivenmember for causing said wall-engaging members to move toward retractedpositions.

24 Claims, 8 Drawing Figures PATENTED M1 1973 SHEET 1 0f 4 Jean PlancheINVENTOR BY Mu hf n ATTORNEY PAIENTEDmnz m2 3.685.158

sum 2 us 4 Jean Planche INVENTOR A T TORNE Y PATENTEB M1822 19123.685.158

sumaura Jean Planche INVEN TOR AT TORNEY FIG. 8

Jean Planche IN VE N TOR BY Max w ATTORNEY SONDES WITH ARTICULATED ARMSUSED IN WELL LOGGING This application is a continuation of applicationSer. No. 770,978 filed Oct. 28, 1968.

This invention relates generally to sonde apparatus for use inconducting measurements in well bores, and more particularly to sondeapparatus having articulated arms carrying wall-engaging members adaptedfor measuring parameters in a well bore.

in measuring various parameters in well bores, such as diameter,resistivity, and dip, sondes equipped with pad members which contact thewalls of the well bore have been used. The pad members may carryelectrodes or transducers, but can sometimes have pressure rollers orshoes in the case of diameter measurements. ln certain prior art sondes,contact of the pad members withthe well bore wall is obtained by meansof long bow springs having their extremities attached to rings whichslide along the body member of the tool. Such an arrangement is shown inUS. Pats. Nos. 2,639,512 and 2,669,690. One disadvantage of this type ofsonde is that the pad members, which slide in intimate contact with thewell bore wall, may wear rapidly. Moreover, lowering of the tool intothe well is sometimes difilcult.

Other types of prior art sondes, which have been arranged to overcomethe foregoing disadvantages, carry pad members mounted on articulatedarms which can be closed when lowering the tool down the well. In onesuch device shown in US. Pat. No. 2,876,413, the pressure of the padmembers against the well bore wall is caused by a coil spring and istransmitted to the articulated arms by a system of rods and sliders.This force transmission system, although quite successful, tends to becomplicated and cumbersome. Furthermore, the coil spring, which mustapply a strong force, is very long. A sonde constructed in this manneris heavy, thereby rendering it somewhat inconvenient when it isnecessary to combine different tools to conduct several measurementsduring one lowering operation down a well. Furthermore, in the case ofdeviated wells, the weight of the sonde has a radial component whichtends to close the arms and to reduce the pressure of the upper padmember, which can then become separated from the well bore wall.Finally, the pressure from the coil spring which is applied to the padsby means of various rods and sliders may cause undue wear in thearticulations.

[t is therefore an object of the present invention to provide a new andimproved sonde apparatus with articulated arms carrying wall-engagingmembers and having considerably reduced dimensions and weight.

A t'urther object of the present invention is to provide a new andimproved sonde apparatus having articulated arms carrying wall-engagingmembers and in which the articulations are subjectedto relatively smallloads throughout the time required to conduct measurements.

These and other objects are attained in accordance with the presentinvention by a sonde apparatus having an elongated body and at least onepair of wall-engaging members, each of said members being linked to saidbody by arms articulated on the said body. Each wallengaging membermoves outwardly of the body under the influence of a spring installedexternally of said body and arranged to press outwardly in the vicinityof the wall-engaging member. Each arm is provided with a crank portionwhich engages on one of two side trunnions of a driven member which canslide longitudinally of the said body. By means of this device, thesprings, which can be installed at approximate arm level, make itpossible to greatly reduce the overall length of the sonde. A padclosing force can be applied directly to the driven member, therebyresulting in a particularly simple force transmission system. Moreover,since the spring pressure is applied very close to the vicinity of thecontact points of the wall-engaging members with the well bore wall, thearticulations are subjected to very little wearing force during thetaking of measurements.

Such a device can be easily adapted to a sonde apparatus carrying twoindependent pairs of wall-engaging members in which the usualtransmission system has heretofore been somewhat complex. In accordancewith another feature of the present invention, a sonde apparatus isprovided with two driven members, one of which slides within the other,the outer driven member carrying two trunnions on which the crankportions of the arms of the first pair of pad members are engaged, theinner driven member carrying two trunnions which pass throughlongitudinal slots in the outer member and on which the crank portionsof the arms of the second pair of pad members engage. Such an assemblycan be used, for example, in an instrument for measuring the two maindiameters of a well bore.

Another particularly interesting application of the present invention isin dip measuring sondes in which the quality of measurements dependsessentially on proper contact of the pads with the well bore wall. Insuch sondes, each pad taken singularly should remain parallel with thelongitudinal axis of the body, and should also have the ability to movealong a course perpendicular to this axis. A sonde apparatus describedin application Ser. No. 2l9,6l9, now US. Pat. No. 3,423,671, has fourpads constructed and arranged whereby these conditions are fulfilled.Each pad is slidably mounted on a support which is linked to the body bymeans of two arms forming the opposite sides of an articulatedparallelogram. Furthermore, each pad is articulated on a lower armforming the main side of a Y" with its center linked to the extremity ofa short side. This short side, which is equal in length to onehalf ofthe main side, is articulated at its other extremity on the body.However, in accordance with the present invention, it is possible tosimplify such a set of arms and to further reduce the weight anddimensions of the tool.

According to another embodiment of the present invention, a sondeapparatus for use in dip measurements has two independent pairs ofwallengaging members installed at right angles to one another, with eachmember being articulated generally as described above. The long sides ofthe "Ys" have the same length as a corresponding main arm, and the shortside arms, having a length equal to one-half the length of acorresponding main arm, each have a crank portion identical to that oneach main arm. The crank portions are engaged on lower trunnions of anaxially movable driven member, the upper and lower trunnions, the mainarms and the short side articulations being arranged in such a mannerthat the main arms and the short arms remain parallel to each otherduring lateral movement of the pad members between retracted andextended positions. As will be explained later, the movements of the padmembers fulfill the conditions given hereabove with a minimum of armsand articulations.

The present invention has other objects and advantages which will becomemore clearly apparent in connection with the following detaileddescription of the structure and operation of various embodimentsthereof, when taken in conjunction with the appended drawings in which:

FIG. 1 is a schematic view of a sonde suspended in a well bore;

FIG. 2 is a longitudinal sectional view of an apparatus in accordancewith the present invention;

FIG. 3 is a perspective view of one of the arms of the sonde illustratedin FIG. 2;

FIG. 4 is a cross-section taken on line 4-4 of FIG. 2;

FIG. 5 is a schematic illustration of a hydraulic system which can beused in the present invention;

FIG. 6 is a perspective view showing further details of the drivenmembers of a sonde with two independent pairs of pad members installedat right angles to one another;

FIG. 7 is a longitudinal sectional view of another embodiment of thepresent invention which can be used for dip measurements; and

FIG. 8 is a longitudinal sectional view of a sonde similar to that ofFIG. 7, but in which the pad pressure is variable.

Referring initially to FIG. 1, a well bore B is shown extending into theearth and traversing earth formations. A sonde S is suspended on anarmored electrical cable or wireline C and is adapted for longitudinalmovement through the well bore. By longitudinal movement is meant amovement parallel to the longitudinal axis of the well bore B which, inthe case of a truly vertical borehole, would be a vertical movement.Movement outwardly to the longitudinal axis of the well bore will, onthe other hand, be referred to as lateral" movement.

Referring now to FIG. 2, an apparatus in accordance with the principlesof the present invention is shown as including an elongated body member10 having a power section 11 at its upper end and a motor section 12 atits lower end. A plurality of arms 13 and 14 are pivotally coupled to anintermediate portion of the body member 10 and are biased outwardlytoward wallengaging positions by spring assemblies 15 and 16. The bodymember 10 is adapted for suspension in a well bore on an electricalcable or wireline 17.

On the central part of the body member 10 are attached pivots ortrunnions and 21 extending perpendicular to the longitudinal axis of thebody member and parallel to each other. On the pivots 20 and 21 arearticulated, respectively, two anns l3 and 14. As shown in FIG. 3, eacharm has parallel side members 22 and 23 which are spaced apart. The sidemember 23 is straight, whereas the opposite side member 22 has a bentextremity forming a crank am 24, the crank arm being provided with anopen-ended groove 25. A shoe 26 is attached to the opposite end of themembers and can have a pressure roller 27 thereon. Another roller 28 canbe placed in close proximity to the shoe 26 between the side members 22and 23. With the arms l3 and 14 equipped with the shoes and pressurerollers as shown, the sonde can be used to measure the diameter of awell bore. For other measurements, it is, of course, possible to replacethe shoes 26 with pad members equipped with transducers or electrodes orthe like.

With further reference to FIG. 2, the spring assemblies l5 and 16 may beformed by multiple leafs, the leafs being constituted by circular bladesof decreasing length placed side-by-sidc so as to obtain a straightshape when arms are in closed position alongside the body member 10. Theinner ends of the spring assemblies are mounted in fittings 30 and 31which can be attached to the body member 10 by pins 32. The other endportions of the spring assemblies rest on the rollers 28 andcontinuously urge the arms 13 and 14 to swing outwardly. When the armsare forced to swing inwardly however, the spring assemblies 15 and 16are flattened and fit perfectly along side the body member 10, resultingin minimum dimensions for the tool.

A driven member 35 is mounted on A the body member 10 and is arranged toslide longitudinally through guides 36 and 37. The member 35 carries twodiametrically opposed trunnions 38 and 39 (FIG. 4) extendingperpendicular to the member axis. The groove 25 in each crank arm 24engages a respective trunnion in such a manner that the extension andretraction of the arms 13 and 14 is symmetrical relative to thelongitudinal axis of the body member 10.

The motor section 12 on the lower portion of the body member I0, isconstituted by a control cylinder 40 and a storage cylinder 41 placed inend-to-end relation and separated by a partition 42. The partition 42has a passage 43 which opens into the interior of the control cylinder40, and a conduit or tube 44 extends from the passage 43 upwardly alongthe body member 10 to the power section 11. The storage cylinder 41 isalso placed in communication with the power section 11 by means of apassage 45 and a conduit 46. To simplify the drawings, only the endportions of the tubes 44 and 46 have been illustrated by phantom lines.Within the control cylinder 40 slides a control piston 47 equipped withseal rings 48 and carrying a shoulder 49 on which a coil spring 50rests. The piston 47 functions to control closing of arms 13 and I4 byforcing the driven member 35 upwardly as will be more fully explainedhereafter. A floating, pressure balancing piston 53 slides freely withinthe storage cylinder 41, the piston 53 being equipped with seal rings54. The balance piston 53 separates the storage cylinder 41 into upperand lower chambers, the lower chamber 56 being in communication withfluids in the well bore, and the upper chamber 57 providing a fluidstorage reservoir. The lower extremity of cylinder 41 may be equippedwith a protective bottom nose or fitting 58.

The motor section 11 has a housing 60 which contains a hydraulic systemshown schematically in FIG. 5. The system includes a hydraulic pressuregenerator such as an electric motor 61 which drives a pump 62 forsupplying fluid under pressure to the conduit 44 through a one-way checkvalve 63, the fluid being supplied via the conduit 46 from the storagechamber 57. A pressure regulator valve 64 can be placed in a conduit 65to control the maximum working pressure of the system. Another conduit66 extends between the conduits 44 and 46 and is provided with a typicalsolenoid-operated valve 67. When the valve 67 is closed and the motor 61and pump 62 actuated, fluid under pressure is supplied to the cylinder40 via the conduit 44 and acts on the piston member 47, forcing thepiston member to drive the member 35 upwardly relative to the bodymember 10. Upward movement of the driven member 35 causes the arms 13and 14 to swing inwardly against the influence of the spring assemblies15 and 16 toward the body member due to the coaction of the crank arms24 and the trunnions 38 and 39. When the arms 13 and 14 are fullyretracted, the motor 61 and the pump 62 can be stopped, and the armswill remain retracted until the solenoid-operated valve 67 is opened toenable fluids to return to the storage chamber 57 via the conduits 66and 46. Of course, the motor 61 and the solenoid-operated valve 67 areelectrically coupled by conductors to conductors within the cable 17, sothat the components can be remotely controlled from the top of theborehole.

The housing 60 also contains measuring equipment. In the drawings, as anexample, a potentiometer 70 is shown in which the cursor is driven by alinkage rod 71 passing through the bottom wall 74 of the housing 60 andattached by a bracket 72 to the driven member 35. Fluid leakage alongthe linkage rod 71 is prevented by a seal ring 73. The variouselectrical controls and the terminals of the potentiometer are coupledto connectors 75 which pass through the upper wall 76 of the housing 60for connection with the conductors in the wireline on cable 17.

in operation, the arms 13 and 14 may be closed, particularly duringlowering into the well bore. The hydraulic system is placed in operationas previously described and is supplied with fluid from storage chamber57 through the passage 45 and the conduit 46. Fluid under pressure isthen delivered through the other conduit 44 and passage 43 into thecontrol cylinder 40 below the piston 47. The fluid pressure developsupward force on the piston 47 which drives the member 35 upwardly. Theforce is applied by the trunnions 38 and 39 to the crank portions 24 ofthe arms 13 and 14, tending to cause the arms to swing in wardly aboutthe pivot pins 20 and 21. Of course, when sufiicient upward force isdeveloped on the member 35 to overcome the tendency of the springassemblies and 16 to urge the arms outwardly, the arms will fold intovertical positions alongside the body member 10. When takingmeasurements in the well bore, the fluid pressure below the controlpiston 47 is reduced as previously described, and it will return to alower position under the influence of the coil spring 50 where there isclearance between the lower end of the member 35 and the piston 47 toenable swinging movement of the arms. The arms 13 and 14 will swingoutwardly under the influence of the spring assemblies 15 and 16 untilthe pressure rollers 27 engage the walls of the well bore. Throughout ameasuring operation, since the points at which outward force is appliedby the spring assemblies 15 and 16 to the arms 13 and 14 is in closeproximity to the wall-engaging rollers 27, the pivot pins and 21 on thebody member 10, and the trunnions 38 and 39 on the driven member 35, aresubjected to very little wearing action.

Thus, it will be appreciated that wear on these various parts isminimal. Furthermore, the very small dimensions of such a sonde and thesimplicity of design should be noted. Theuse of the axially movabledriven member 35 enables, in particular, placing of the piston 47 at thelower part of the sonde with the piston no longer engendering thrust.Location of the oil storage cylinder 41 at the lower portion of thisbody member 10 enables further reduction in the longitudinal dimensionsof the sonde.

Although only two arms have been illustrated in FIG. 2, this device isreadily adaptable to a structure with four arms and in which each pairof arms is independent of the other so as to form a double caliper. Inactual fact, it suffices to mount two concentric driven members, onewithin the other, each of the members being coupled with a pair of arms.The upper portions of two such members 350 and 35b are illustrated inFIG. 6. Member 35a, in similar manner to the element 35 in FIG. 2, isequipped with diametrically opposed trunnions 38a and 39a. The member350 is hollow and has two longitudinal slots 79 and 80 located in aplane perpendicular to the axis of trunnions 38a and 390. A seconddriven member 35b, capable of telescopic reception within the member350, has a transversely extending hole in which a shaft 81 passingthrough the longitudinal slots 79 and 80 in member 350 is mounted. Thedriven members 35a and 35b are mounted on the body member of the sondein an identical manner to that shown in FIG. 2, but carrying twoadditional main arms equipped with blade springs and located in a planeperpendicular to the plane passing through arms 13 and 14. The grooves25 of crank arms 24 and 25 engage the trunnions 38a and 39a, and thegrooves of the additional arms engage the end portions of the shaft 81.Thus, a sonde with two identical pairs of arms of very simplemanufacture is obtained. In particular, note should be taken of the factthat the four arms are identical to those illustrated in FIG. 3, therebyenabling a reduction in the cost of manufacture. Brackets 72a and 72bcan be mounted on the respective members 35a and 35b in such a manner asto control two different potentiometers giving readings of the two maindiameters of the well bore.

FIG. 7 illustrates another embodiment of the present invention which isparticularly suited for dip measurement operations. The sonde carriesfour pads, only two of which are shown in the drawings to simplify theillustration. in similar manner to the embodiment shown in FIG. 2, anelongated body member 1 10 has at its upper portion a sealed powersection 111, and, at its lower portion, a motor section 112 including apower cylinder 140 and a storage cylinder 141 separated by a partition142. A power piston 147 slides within the cylinder 140, whereas apressure balancing piston 53 slides within the storage cylinder 14].Blade spring assemblies and 1 16 are attached to the body member 110 byrespective fittings 130 and 131 and have their free ends slidablyengaging pad structures 183 and 184.

The main arms 113 and 114 are articulated or pivoted on pivot pins and121. Each of these arms has two side members 122 and 123, one memberhaving a bent crank arm 124 with a groove 125 which engages on the endportions of a shaft 181 mounted on an inner driven member b and passingthrough longitudinal slots 179 in the outer driven member 135a. Theother pair of pad members are articulated on the body member 110 in thesame manner and have crank arms coacting with side trunnions on theouter member 135a in the same manner as shown in FIG. 6.

The pad structures 183 and 184, which may be equipped with typicalmeasuring electrodes, are slidably mounted on supports 185 and 186.These supports are articulated on the main arms 113 and 114 by means ofpivot pins 187 and 188. The lower ends of the pad structures 183 and 184are articulated on the body member 110 by means of a system of Y" shapedarm configurations, each configuration having a long side 189 or 190 ofthe same length as the main arms 113 and 114, and a short side 191 or192. Each of the long sides 189 or 190 has three pivot connections: onepivot 193 or 194 is articulated on the pad; the second pivot 195 or 196slides in a longitudinal slot 197 or 198 in the body member 1 thecentral pivot 199 or 200 located at an equal distance from pivots 193and 195 (or 194 and 196) is articulated on the short side 191 and 192.The short sides 191 or 192 are articulated at pivot points 201 or 202 onthe body member 110 and have two side members of unequal length, thelongest of the two side members having a crank arm 203 and a slot 204which is engaged on one of the two lower trunnions 205 on the innerdriven member 135b. The distance between pivot points 199 and 201 of ashort side 191 is equal to one-half the distance between the pivotpoints 193 and 195 of a long side 189. The same is the case for the Y"system articulation for the other pad'structures. The length of thedriven member 135b between the trunnions 205 and 181 is equal to thedistance between pivots 120 and 202. Thus it will be appreciated that ifthe pivot points 120, 188, 194, 196, 200 and 202 are termed,respectively, A-B-C-D-E-F, then by the very construction of the arms,AB=CD=2 EF=2EC=2DE. Furthermore, the side EF remains parallel to sideAB. The result is that DFC is a right triangle with DC being thehypotenuse. In other respects, since DFE is an isosceles triangle, angleFDE is equal to angle EFD which, itself, is equal to BAF. OuadrilateralABCD is, therefore, arranged in such a manner that the pad structureside remains parallel to AD, and to the axis of the sonde. Accordingly,the pad structures 183 and 184 separate from the sonde with a movementperpendicular to its longitudinal axis, and remain constantly parallelwith this axis.

As previously mentioned, the sonde also has two other pad structureslocated in a plane passing through the longitudinal axis of the bodymember 110 and perpendicular to the section plane on the figure. Thesepads, together with their articulated arms, are in every way identicalto the pad structures 183 and 184 and are attached to an outer drivenmember 1350 within which the inner member 135b slides in the same manneras previously described with reference to FIG. 6. Linkages couple theupper ends of the members 135a and 135b to respective cursors ofpotentiometers as described with respect to FIG. 2. Thus, a dipmeasurement probe is provided with two independent pairs of padstructures located at right angles to one another and fulfilling themobility conditions previously described, and is attained in a verysimple manner. In particular, note should be taken of the fact that thearticulations used leaves enough free space for the spring assemblies,thereby making it possible to use this device without increasing theradial dimensions of the sonde. Further note should be taken of the factthat the pressure force of the spring assembler is applied directlyinwardly of the pad structures in such a manner that the various pivotpoints are subjected to minimal wear force throughout the time taken toconduct measurements. Finally, the weight and dimensions have beenreduced practically by one-half relative to conventional sondes. Inorder to perfect this result, it is possible to make the great majorityof the components out of a lightweight metal such as titanium.

It is also possible to provide a spring fitting constructed and arrangedin such a manner as to make the spring pressure vary according to thecharacteristics of the measuring operation (e.g., diameter, deviation).As shown in FIG. 7, the fittings 130 and 131, which can rotate aroundpivot pins 120 and 121, are locked by pins 207 and 208. By providing forseveral pin holes such as 209 and 209' for the pins 207 and 208, it ispossible to place the base of the spring assemblies and 116 at differentangles. It is thus possible to select stronger pressures for largediameter or highly deviated well conditions.

To obtain several pad pressures, it is also possible to obtain a set ofsprings with different spring rates. It then sufi'lces to select thespring rates suitable for the conditions of the well and to mount themon the member by means of pins 207 and 208 and pivots and 121. Noteshould be taken of the ease with which these spring changes can beconducted relative to former devices in which the coil springcontrolling the arm separation was located within the sonde member.

FIG. 8 illustrates a dip measurement sonde in which the outward pressureof the pads can be remotely controlled. On the body member 210 arearticulated pads 283 and 284 which separate under the influence ofsprings 21S and 216 in the same manner as described with reference toFIG. 5. This embodiment is, furthermore, equipped with a pad pressurecontrol device. The fittings 230 and 231 of the springs 21S and 216 aremounted on pivot pins 220 and 221. At the upper extremity of thefittings are installed rollers 21] and 212 which rest on the slopes ofthe internal surfaces of a slider 213. The slopes are inclined relativeto the axis of the sonde at their upper part and are parallel to thisaxis on their lower part. The slider 213 is coupled to a central rod 218sliding within a driven member 235, the slider being attached bytransverse members extending through elongated lost-motion slots in thewall of the member 235. In the case where the sonde carries twoindependent pairs of pads, the driven member 235 may consist of twoconcentric tubes as illustrated in FIG. 6, with the inner tube having abore in which the central rod 218 is slidably received. The central rod218 carries a flange 219 at its lower end and screws into a power piston247. The piston 247 is double acting, that is to say, that oil underpressure can be applied selectively to its lower surface or its uppersurface. The piston 247 can move within a cylinder 240 having passages243 and 245 capable of being alternately connected to the outlet of ahydraulic pressure generator located in the upper housing 260 of thetool. A seal ring 217 prevents fluid leakage between the cylinder 240and the driven member 235. In similar manner to the previously describedembodiments, the body member carries an oil storage cylinder orreservoir 241 closed by a floating balance piston 253 at its lowerportion.

In FIG. 8, the sonde is illustrated in measuring position with maximumblade spring force. To reduce the pad pressure, oil is delivered to thelower part of the control cylinder 240. The piston moves upwardly,driving the member 235 which moves the slider 213 upwardly. The rollers21 1 and 212 can move outwardly of the axis of the sonde, and thefittings 230 and 231 can rotate about the pivot pins 220 and 221, thusreducing the force applied by the springs 215 and 216 to the pads 283and 284. The power piston 247 remains at the height engendered by thedesired pressure if the hydraulic pressure generator is stopped. Theminimum pressure is obtained when the rollers 211 and 212 rest on thoseparts of the slopes of the slider 213 which are parallel to thelongitudinal axis of the sonde. in this position, the flange 219 is atthe end of its travel and against the lower surface of the driven member235 and the pads are separated at maximum distance. If an upwardmovement continues to be engendered in the piston 247, the flange 219pushes the driven member 235 upwardly and closes the pads. The openingor reverse movement of the pads is obtained by delivering oil underpressure into the upper part of control cylinder 240 via the passage245. The relative position of the driven member 235 can be taken bymeans of a potentiometer (not shown) placed, for example, in the sealedhousing 260 and in which the cursor is attached to the driven member bymeans of a linkage or rod 271 similar to that used in the embodimentpreviously described for measuring diameters.

Of course, the invention is not limited to the details describedhereabove. The few examples illustrated in the drawings show, in actualfact, that the invention can be adapted to numerous types of sondes,with two or four pads, diameter taking or dip measuring sondes, andsondes with fixed or variable pad pressure. The pads can be equippedwith electrodes or any other transducer according to the type ofmeasurement desired.

A new and improved sonde apparatus having articulated arms has beendisclosed. The apparatus is constructed and arranged for minimumdimensions and weight, and the various pivot connections are subjectedto reduced wearing action during use. Since various changes ormodifications will be apparent to those skilled in the art withoutdeparting from the inventive concepts involved, it is the aim of theappended claims to cover all such changes and modifications fallingwithin the true spirit and scope of the present invention.

What is claimed is:

1. In an apparatus for use in making measurements in a well bore, a bodymember adapted to be moved longitudinally through a well bore; aplurality of arms attached to said body member, one end portion of eacharm having a pivot connection to said body member so that said arms aremovable by pivotal rotation between retracted positions alongside saidbody member and extended positions at an angle to the longitudinal axisof said body member; guide means on said body member above said pivotconnections, said guide means functioning to guide a driven memberslidable longitudinally along said body member and extending betweenlocations above said guide means and below said pivot connections;coupling means between the pivoted end of each arm and said drivenmember arranged so that longitudinai movement of said driven member istranslated to pivotal rotation of said arms, and vice-versa; springmeans mounted to the sides of said body member and having portionsextending outwardly thereof arranged and adapted to continuously urgepivotal rotation of said arms toward extended positions; and selectivelyoperable motor means carried by said body member below said drivenmember and adapted to contact the lower end thereof to force said drivenmember along said body member in a direction to cause pivotal rotationof said arms to retracted positions, said motor means being out ofcontact with said driven member during measuring operations so that saidarms can pivot about said pivot connections independently of said motormeans.

2. The apparatus of claim 1 wherein said spring means is constituted bya plurality of arcuate members, each of said arcuate members comprisingat least one blade having one end arranged to press outwardly on'arespective one of said arms.

3. The apparatus of claim 1 wherein said selectively operable motormeans includes piston and cylinder means, one of which is attached tosaid body member and the other of which is engageable with the lower endof said driven member; and means for supplying fluid under pressure tosaid piston and cylinder means.

4. The apparatus of claim 3 further including a reservoir below saidpiston and cylinder means for storing fluid supplied to said piston andcylinder means.

5. The apparatus of claim 4 further including means for balancing thepressure of fluids in said storage chamber with the hydrostatic pressureof fluids in a well bore.

6. The apparatus of claim 1 wherein a majority of the structuralcomponents of said combination are constructed of a light-weight metalsuch as titanium.

7. Apparatus for use in making measurements in a well bore, comprising:a body member adapted to be moved longitudinally through a well bore;two independent pairs of arms located at right angles around said bodymember, one end portion of each arm having a pivot connection to saidbody member so that said arms are movable by pivotal rotation betweenretracted positions alongside said body member and extended positions atan angle to the longitudinal axis of said body member; guide means onsaid body member above said pivot connections, said guide meansfunctioning to guide two independently slidable driven members movablelongitudinally along said body member, each driven member extendingbetween locations above said guide means and below said pivotalconnections; coupling means between the pivoted end portions of eachpair of arms and a respective one of said driven members arranged sothat longitudinal movement of each driven member is translated topivotal rotation of a respective pair of said arms, and vice versa;spring means mounted to the sides of said body member and havingportions extending outwardly thereof in the plane of pivotal rotation ofeach pair of arms and arranged and adapted to continuously urge pivotalrotation of said arms toward extended positions; and selectivelyoperable motor means carried by said body member below said drivenmembers and adapted to contact the lower ends thereof to force saiddriven members jointly along said body member in a direction to causepivotal rotation of said arms to said retracted positions, said motormeans being out of contact with both of said driven members duringmeasuring operations so that said arms can pivot about said pivotconnections independently of said motor means.

8. The apparatus of claim 7 wherein said driven members compriseconcentrically disposed tubes, said coupling means coupling the innerone of said tubes to one pair of said arms and the outer one of saidtubes to the other pair of said arms.

9. The apparatus of claim 7 wherein said driven members compriseconcentrically disposed tubes, the inner tube carrying a transverselydisposed trunnion pin having end portions extending throughlongitudinally extending elongated slots in the wall of the outer tube,said outer tube having oppositely disposed trunnions located at rightangles with respect to said trunnion pin, said coupling means comprisingcrank means on the end portions of each arm, the crank means for onepair of arms having sliding connections with the end portions of saidtrunnion pin, the crank means for the other pair of arms having slidingconnections with said oppositely disposed trunnions.

10. The apparatus of claim 7 wherein said motor means includes pistonand cylinder means on said body member, said piston means beingengageable with the lower ends of said driven members; means forsupplying fluid under pressure to said piston and cylinder means tocause said piston means to engage said driven members; and biasing meansfor urging said piston means out of engagement with said driven membersduring measuring operations.

11. The apparatus of claim 10 further including a reservoir for storingfluid to be supplied to said piston and cylinder means.

12. The apparatus of claim 11 wherein said reservoir and said piston andcylinder means are formed in endto-end relationship; and a partitionseparating said reservoir and said cylinder means.

13. The apparatus of claim 11 further including means for balancing thepressure of fluids in said reservoir with the hydrostatic pressure offluids in the well bore.

14. In an apparatus for use in making measurements in a well bore, anelongated boys having upper and lower axially disposed guide means and adriven member slidable through said guide means; at least one pair ofoppositely disposed anns, each arm having one end pivotally connected tosaid body intermediate said guide means, the pivot connections for arespective pair of said arms being disposed on lateral opposite sides ofsaid driven member; coupling means on said driven member and said armsfor translating pivotal rotation of said arms about said pivotalconnections to axial sliding movement of said driven member with respectto said body; spring means including elongated blade structures, eachhaving one end connected to an upper portion of said body and the otherend pressing against a respective one of said arms, arranged tocontinuously urge the other ends of said arms outwardly of said body;means for varying the pressure with which said blade structures pressagainst said arms; and selectively operable motor means carried by saidbody below said lower guide means for forcing axial sliding movement ofsaid driven member with respect to said body in a direction to causeinward movement of said other ends of said arms.

15. Apparatus for use in making measurements in a well bore, comprising:an elongated body body adapted to be lowered into a well bore on acable, said body member having axially disposed guide means and a drivenmember slidable along said body member through said guide means; atleast one pair of wall-engaging pad structures, each of said padstructures being mounted for lateral movement relative to said bodymember between retracted positions alongside said body member andextended positions engaging a well bore wall; arm means having pivotalconnections to said body member for mounting said pad structures on saidbody member in a manner to enable said movement between retracted andextended positions; coupling means on said arm means and said drivenmember for translating pivotal rotation of said arm means about saidpivotal connections to axial sliding motion of said driven member withrespect to said body member; spring means including arcuate membersextending outwardly of said body member, said arcuate members comprisingblades having one end attached to said body member and the other endslidably engaging a respective pad structure and arranged to pressagainst said pad structures behind central portions thereof for urgingsaid pad structures laterally outwardly into engagement with a well borewall; and selectively operable motor means carried by said body memberbelow said guide means and said driven member and adapted for forcingaxial movement of said driven member and corresponding pivotal rotationof said arm means in a direction to move said pad structures laterallyinwardly of said body member and into positions alongside said bodymember to enable substantial running clearance of said apparatus in awell bore.

16. The apparatus of claim 15 wherein said selectively operable motormeans includes piston and cylinder means, one of said piston andcylinder means being to engage said driven member, and means forsupplying fluid under pressure to said piston and cylinder means.

17. The apparatus of claim 15 wherein each of said arm means includes aplurality of pivotally connected links constructed and arranged todefine, together with said body member and pad structures, anarticulated quadrilateral in such a manner that the pad structuresremain parallel to the longitudinal axis of said body member duringlateral inward and outward movement relative to said body member.

18. Apparatus for use in making measurements in a well bore, comprising:an elongated body; two independent pairs of pad structures located atright angles around said body, said pad structures being movablelaterally inwardly and outwardly of said body; arm means forarticulating said pairs of pad structures on said body member, the endsof said ann means being pivotally attached to said body and said padstructures in a manner whereby lateral movement of said pad structurescorresponds to pivotal rotation of said arm means; spring meansincluding a plurality of arcuate blade structures, each blade structurehaving one end mounted to the side of said body and the other endpressing outwardly against a respective pad structure for biasing saidpad structures outwardly; first and second concentrically arrangeddriven members on said body movable longitudinally relative to oneanother and to said body; means for translating pivotal rotation of thearm means for respective pairs of said pad structures to longitudinalmovement of respective ones of said first and second driven members;said first and second members being adapted for coupling to means fordetecting the extent of longitudinal movement of said driven membersrelative to said body; and selectively operable motor means carried bysaid body below said first and second driven members and adapted tojointly move said first and second driven members in a longitudinaldirection with respect to said body to cause pivotal rotation of saidarm means and lateral inward movement of said pad structures.

19. The apparatus of claim 18 further including means for increasing ordecreasing the bias force afforded by said blade structures tocorrespondingly increase or decrease the amount of pressure exerted bythe pad structures against a well bore wall.

20. In an apparatus for use in investigating earth formations traversedby a borehole, the combination comprising: an elongated body memberadapted for longitudinal movement through a borehole; a plurality ofwall-engaging members movable between retracted positions alongside saidbody member and extended positions engaging a well bore wall; slidemembers upon which said wall engaging members are slidably mounted, saidslide members being coupled to said body member and arranged to movelongitudinally with respect to said body member and said wall-engagingmembers; a plurality of main arms coupling different slide members tosaid body member; linkage means connected between said wall-engagingmembers and said body member, said linkage means being arranged forpermitting transverse movement of said wall-engaging members withrespect to said body member while preventing longitudinal movementtherebetween; spring means for forcing said wall-engaging membersagainst the well bore wall with a preselected pressure, said springmeans including a plurality of blade springs, each having one endattached to said body member and its other end slidably engaging arespective slide member at a point behind the center portion of therespective wall-engaging member; and remotely and selectively operablemeans for maintaining said wallengaging members in retracted positionduring longitudinal movement in a well bore, including a driven meansmovable axially of said body member and coupled to said main arms andsaid linkage means, means for retracting said wall-engaging members inresponse to upward longitudinal movement of said driven means, and motormeans for driving said driven means upwardly relative to said bodymember.

21. The apparatus of claim 20 wherein said motor means includes ahydraulically operated piston and cylinder means located on said bodymember below said driven means, one of said piston and cylinder meansbeing coupled in force transmitting relationship to said driven means.

22. The apparatus of claim 21 further including a storage reservoir forstoring fluid to operate said piston 2st as sesas' s'aaesmt'zssslsastsimeans.

23. The apparatus of claim 20 wherein said retracting means includescrank arms on said main arms and at least some of said linkage means,projections on said driven means, and sliding connections between saidcrank arms and said projections.

24. The apparatus of claim 20 wherein the majority of structuralcomponents of said combination are constructed of a light-weight metalsuch as titanium.

1. In an apparatus for use in making measurements in a well bore, a bodymember adapted to be moved longitudinally through a well bore; aplurality of arms attached to said body member, one end portion of eacharm having a pivot connection to said body member so that said arms aremovable by pivotal rotation between retracted positions alongside saidbody member and extended positions at an angle to the longitudinal axisof said body member; guide means on said body member above said pivotconnections, said guide means functioning to guide a driven memberslidable longitudinally along said body member and extending betweenlocations above said guide means and below said Pivot connections;coupling means between the pivoted end of each arm and said drivenmember arranged so that longitudinal movement of said driven member istranslated to pivotal rotation of said arms, and vice-versa; springmeans mounted to the sides of said body member and having portionsextending outwardly thereof arranged and adapted to continuously urgepivotal rotation of said arms toward extended positions; and selectivelyoperable motor means carried by said body member below said drivenmember and adapted to contact the lower end thereof to force said drivenmember along said body member in a direction to cause pivotal rotationof said arms to retracted positions, said motor means being out ofcontact with said driven member during measuring operations so that saidarms can pivot about said pivot connections independently of said motormeans.
 2. The apparatus of claim 1 wherein said spring means isconstituted by a plurality of arcuate members, each of said arcuatemembers comprising at least one blade having one end arranged to pressoutwardly on a respective one of said arms.
 3. The apparatus of claim 1wherein said selectively operable motor means includes piston andcylinder means, one of which is attached to said body member and theother of which is engageable with the lower end of said driven member;and means for supplying fluid under pressure to said piston and cylindermeans.
 4. The apparatus of claim 3 further including a reservoir belowsaid piston and cylinder means for storing fluid supplied to said pistonand cylinder means.
 5. The apparatus of claim 4 further including meansfor balancing the pressure of fluids in said storage chamber with thehydrostatic pressure of fluids in a well bore.
 6. The apparatus of claim1 wherein a majority of the structural components of said combinationare constructed of a light-weight metal such as titanium.
 7. Apparatusfor use in making measurements in a well bore, comprising: a body memberadapted to be moved longitudinally through a well bore; two independentpairs of arms located at right angles around said body member, one endportion of each arm having a pivot connection to said body member sothat said arms are movable by pivotal rotation between retractedpositions alongside said body member and extended positions at an angleto the longitudinal axis of said body member; guide means on said bodymember above said pivot connections, said guide means functioning toguide two independently slidable driven members movable longitudinallyalong said body member, each driven member extending between locationsabove said guide means and below said pivotal connections; couplingmeans between the pivoted end portions of each pair of arms and arespective one of said driven members arranged so that longitudinalmovement of each driven member is translated to pivotal rotation of arespective pair of said arms, and vice versa; spring means mounted tothe sides of said body member and having portions extending outwardlythereof in the plane of pivotal rotation of each pair of arms andarranged and adapted to to continuously urge pivotal rotation of saidarms toward extended positions; and selectively operable motor meanscarried by said body member below said driven members and adapted tocontact the lower ends thereof to force said driven members jointlyalong said body member in a direction to cause pivotal rotation of saidarms to said retracted positions, said motor means being out of contactwith both of said driven members during measuring operations so thatsaid arms can pivot about said pivot connections independently of saidmotor means.
 8. The apparatus of claim 7 wherein said driven memberscomprise concentrically disposed tubes, said coupling means coupling theinner one of said tubes to one pair of said arms and the outer one ofsaid tubes to the other pair of said arms.
 9. The apparatus of claim 7wherein said driven members comprise concentrically disposed tubes, theinner tube carryIng a transversely disposed trunnion pin having endportions extending through longitudinally extending elongated slots inthe wall of the outer tube, said outer tube having oppositely disposedtrunnions located at right angles with respect to said trunnion pin,said coupling means comprising crank means on the end portions of eacharm, the crank means for one pair of arms having sliding connectionswith the end portions of said trunnion pin, the crank means for theother pair of arms having sliding connections with said oppositelydisposed trunnions.
 10. The apparatus of claim 7 wherein said motormeans includes piston and cylinder means on said body member, saidpiston means being engageable with the lower ends of said drivenmembers; means for supplying fluid under pressure to said piston andcylinder means to cause said piston means to engage said driven members;and biasing means for urging said piston means out of engagement withsaid driven members during measuring operations.
 11. The apparatus ofclaim 10 further including a reservoir for storing fluid to be suppliedto said piston and cylinder means.
 12. The apparatus of claim 11 whereinsaid reservoir and said piston and cylinder means are formed inend-to-end relationship; and a partition separating said reservoir andsaid cylinder means.
 13. The apparatus of claim 11 further includingmeans for balancing the pressure of fluids in said reservoir with thehydrostatic pressure of fluids in the well bore.
 14. In an apparatus foruse in making measurements in a well bore, an elongated body havingupper and lower axially disposed guide means and a driven memberslidable through said guide means; at least one pair of oppositelydisposed arms, each arm having one end pivotally connected to said bodyintermediate said guide means, the pivot connections for a respectivepair of said arms being disposed on lateral opposite sides of saiddriven member; coupling means on said driven member and said arms fortranslating pivotal rotation of said arms about said pivotal connectionsto axial sliding movement of said driven member with respect to saidbody; spring means including elongated blade structures, each having oneend connected to an upper portion of said body and the other endpressing against a respective one of said arms, arranged to continuouslyurge the other ends of said arms outwardly of said body; means forvarying the pressure with which said blade structures press against saidarms; and selectively operable motor means carried by said body belowsaid lower guide means for forcing axial sliding movement of said drivenmember with respect to said body in a direction to cause inward movementof said other ends of said arms.
 15. Apparatus for use in makingmeasurements in a well bore, comprising: an elongated body adapted to belowered into a well bore on a cable, said body member having axiallydisposed guide means and a driven member slidable along said body memberthrough said guide means; at least one pair of wall-engaging padstructures, each of said pad structures being mounted for lateralmovement relative to said body member between retracted positionsalongside said body member and extended positions engaging a well borewall; arm means having pivotal connections to said body member formounting said pad structures on said body member in a manner to enablesaid movement between retracted and extended positions; coupling meanson said arm means and said driven member for translating pivotalrotation of said arm means about said pivotal connections to axialsliding motion of said driven member with respect to said body member;spring means including arcuate members extending outwardly of said bodymember, said arcuate members comprising blades having one end attachedto said body member and the other end slidably engaging a respective padstructure and arranged to press against said pad structures behindcentral portions thereof for urging said pad structures laterallyoutwardly into engagemEnt with a well bore wall; and selectivelyoperable motor means carried by said body member below said guide meansand said driven member and adapted for forcing axial movement of saiddriven member and corresponding pivotal rotation of said arm means in adirection to move said pad structures laterally inwardly of said bodymember and into positions alongside said body member to enablesubstantial running clearance of said apparatus in a well bore.
 16. Theapparatus of claim 15 wherein said selectively operable motor meansincludes piston and cylinder means, one of said piston and cylindermeans being adapted to engage said driven member, and means forsupplying fluid under pressure to said piston and cylinder means. 17.The apparatus of claim 15 wherein each of said arm means includes aplurality of pivotally connected links constructed and arranged todefine, together with said body member and pad structures, anarticulated quadrilateral in such a manner that the pad structuresremain parallel to the longitudinal axis of said body member duringlateral inward and outward movement relative to said body member. 18.Apparatus for use in making measurements in a well bore, comprising: anelongated body; two independent pairs of pad structures located at rightangles around said body, said pad structures being movable laterallyinwardly and outwardly of said body; arm means for articulating saidpairs of pad structures on said body member, the ends of said arm meansbeing pivotally attached to said body and said pad structures in amanner whereby lateral movement of said pad structures corresponds topivotal rotation of said arm means; spring means including a pluralityof arcuate blade structures, each blade structure having one end mountedto the side of said body and the other end pressing outwardly against arespective pad structure for biasing said pad structures outwardly;first and second concentrically arranged driven members on said bodymovable longitudinally relative to one another and to said body; meansfor translating pivotal rotation of the arm means for respective pairsof said pad structures to longitudinal movement of respective ones ofsaid first and second driven members; said first and second membersbeing adapted for coupling to means for detecting the extent oflongitudinal movement of said driven members relative to said body; andselectively operable motor means carried by said body below said firstand second driven members and adapted to jointly move said first andsecond driven members in a longitudinal direction with respect to saidbody to cause pivotal rotation of said arm means and lateral inwardmovement of said pad structures.
 19. The apparatus of claim 18 furtherincluding means for increasing or decreasing the bias force afforded bysaid blade structures to correspondingly increase or decrease the amountof pressure exerted by the pad structures against a well bore wall. 20.In an apparatus for use in investigating earth formations traversed by aborehole, the combination comprising: an elongated body member adaptedfor longitudinal movement through a borehole; a plurality ofwall-engaging members movable between retracted positions alongside saidbody member and extended positions engaging a well bore wall; slidemembers upon which said wall engaging members are slidably mounted, saidslide members being coupled to said body member and arranged to movelongitudinally with respect to said body member and said wall-engagingmembers; a plurality of main arms coupling different slide members tosaid body member; linkage means connected between said wall-engagingmembers and said body member, said linkage means being arranged forpermitting transverse movement of said wall-engaging members withrespect to said body member while preventing longitudinal movementtherebetween; spring means for forcing said wall-engaging membersagainst the well bore wall with a preselected pressure, said springmeans including a plurality of blade springs, Each having one endattached to said body member and its other end slidably engaging arespective slide member at a point behind the center portion of therespective wall-engaging member; and remotely and selectively operablemeans for maintaining said wall-engaging members in retracted positionduring longitudinal movement in a well bore, including a driven meansmovable axially of said body member and coupled to said main arms andsaid linkage means, means for retracting said wall-engaging members inresponse to upward longitudinal movement of said driven means, and motormeans for driving said driven means upwardly relative to said bodymember.
 21. The apparatus of claim 20 wherein said motor means includesa hydraulically operated piston and cylinder means located on said bodymember below said driven means, one of said piston and cylinder meansbeing coupled in force transmitting relationship to said driven means.22. The apparatus of claim 21 further including a storage reservoir forstoring fluid to operate said piston and cylinder means, said reservoirbeing located on said body member adjacent said piston and cylindermeans.
 23. The apparatus of claim 20 wherein said retracting meansincludes crank arms on said main arms and at least some of said linkagemeans, projections on said driven means, and sliding connections betweensaid crank arms and said projections.
 24. The apparatus of claim 20wherein the majority of structural components of said combination areconstructed of a light-weight metal such as titanium.